Lithography system comprising a coupling for separating line portions, and method for leak testing

Abstract

The invention relates to a lithography system, in particular an EUV lithography system, comprising: a temperature-control device that has at least one line for a liquid to flow through. The line comprises two line portions (31a, 31b) which are connected to one another by means of a coupling (33). The coupling (33) has two detachably connected coupling parts (33a, 33b), into each of which one line end (35a, 35b) of one of the two line portions (34a, 34b) opens. The coupling parts (33a, 33b) each have a ball valve (37a, 37b) for shutting off or opening the associated line end (35a, 35b), or the coupling parts (33a, 33b) together form a ball valve (37). The invention also relates to a method for leak testing the coupling (33).

Description

[0001] Lithography system with a coupling for separating line sections and method for leak testing

[0002] This application claims priority from German patent application DE102023211332.5 of 14 November 2023, the entire

[0003] Disclosure content is incorporated by reference into the content of this application.

[0004] The invention relates to a lithography system, in particular an EUV lithography system, comprising: a device, in particular a temperature control device, which has at least one line for the flow of a liquid. The invention also relates to a method for leak testing. The lithography system or the semiconductor technology system can be a lithography system for exposing a wafer or another optical arrangement of semiconductor lithography, for example an inspection system, e.g. for inspecting masks, wafers or the like used in lithography. In particular, the lithography system can be an EUV lithography system operated with EUV radiation at wavelengths between 5 nm and 30 nm.

[0005] In lithography systems, especially in lithography machines, a liquid is typically used to control the temperature of structural components and optics. This liquid flows through one or more lines of a temperature control device, which typically has a temperature control circuit or is designed as a temperature control circuit. Temperature control often involves cooling, which is why the term "cooling" is used below instead of the term "temperature control." In principle, however, it is also possible to control the temperature of the structural components and optics of a lithography system, i.e., to cool and / or heat them.

[0006] If the structural components and / or optics are to be cooled, a coolant is used which flows in a cooling circuit from a heat sink outside the lithography system to heat sources inside the lithography system and back. The heat sources can be located, for example, in the projection optics, an illumination optics or a light source of an EUV lithography system. If a cooled module needs to be replaced or if cooling lines are in the way of reaching an uncooled component of the lithography system in the field, i.e. during use at the customer's site, it is necessary to open the cooling lines and close them again after the corresponding process, e.g. replacing the component, has been completed. To enable this, the corresponding cooling circuit is emptied and dried. After resealing, a leak test of the cooling circuit is carried out and the cooling circuit is refilled.However, drying the cooling circuit and its cooling lines as well as the leak test involve a great deal of effort.

[0007] Object of the invention

[0008] The object of the invention is to provide a lithography system with a temperature control device whose lines can be opened without having to be emptied before opening.

[0009] Subject of the invention

[0010] This object is achieved by a lithography system of the type mentioned at the outset, in which the or at least one line comprises two line sections which are connected to one another by means of a coupling, wherein the coupling has two detachably connected coupling parts, into which a line end of one of the two line sections opens, and wherein the coupling parts each have a ball valve for blocking or releasing the respective line end or wherein the coupling parts together form a ball valve.

[0011] Couplings are known from the pharmaceutical industry or hydraulics technology that allow fluid-filled lines to be opened with virtually no fluid leakage. However, such couplings cannot be used for lithography systems because they incorporate a partially automatic closure mechanism that influences the fluid flow during operation in such a way that eddies are created that are unacceptable for lithography applications and lead to flow-induced vibrations (ENGI, "flow-induced vibrations", FIV). The inventors recognized that it is advantageous to use ball valves to implement a coupling for opening a fluid-filled line in a temperature control device of a lithography system, as these have a cylindrical internal geometry or a cylindrical passage opening.This internal geometry corresponds to the cylindrical geometry of the pipe sections and thus prevents the occurrence of vortex formation.

[0012] In addition, ball valves can be closed when the coupling is opened so that little or no fluid escapes from the fluid-filled line sections. In particular, the amount of fluid that escapes when the coupling is opened can be limited to a few microliters. Therefore, couplings with ball valves can be used in lithography systems without the fluid that may escape when the coupling is opened causing contamination and damage to nearby machine parts, for example, due to corrosion, and in the worst case, rendering them unusable.

[0013] The realization of the coupling of fluid lines using ball valves is basically known from other fields of technology.

[0014] In DE 100 19 526 A1 it is proposed, for example, to use a ball valve for refueling motor vehicles with liquid natural gas, which consists of two essentially hemispherical valve halves, one of which is assigned to a first fluid line and the other to a second fluid line.

[0015] DE 36 02 775 A1 describes a coupling for connecting a stationary pipe or the like to a movable pipe or hose, which is connected, for example, to a container, tank, or the like. In the coupling described therein, each coupling half is designed as a ball valve. One of the balls of the ball valves can contain a spherical cap-shaped recess such that the balls engage with each other in the closed position.

[0016] However, in lithography systems, especially in EUV lithography systems, the use of couplings that can separate two lines filled with a liquid has so far been avoided due to the problem of causing flow-induced vibrations and the risk of unwanted liquid leakage within the lithography system.

[0017] In one embodiment, a ball of the first ball valve of the first coupling part has a spherical cap-shaped recess into which a ball of the second ball valve of the second coupling part engages, at least when the two ball valves are in a position that blocks the line ends. As described in DE 36 02 775 A1, this prevents a cavity from forming between the two ball valves, from which fluid could escape when the two coupling parts are separated.

[0018] In a further embodiment, the first ball valve has a first actuating element for rotating the ball of the first ball valve and the second ball valve has a second actuating element for rotating the ball of the second ball valve, wherein the first actuating element can only be actuated when the second ball valve is in an open position and the second actuating element can only be actuated when the first ball valve is in a closed position, or vice versa. In this way, it can be ensured that the actuation sequence is maintained both when opening the connection or releasing the coupling parts and when closing the coupling to allow the fluid to flow through. During actuation, the respective actuating element is typically rotated by 90° between the open and closed positions. End stops for the actuating elements can be provided for defined end positions.

[0019] The actuating elements can be designed in different ways to maintain the actuating sequence. For example, the actuating elements can be designed in the manner of actuating pins that are aligned parallel to one another and connected to the respective ball or formed integrally with the respective ball. The two actuating elements can have a section in the axial direction with a circular edge or with a circular outer contour, in which recesses or cutouts are provided. If the circular edges of the two actuating elements arranged next to one another overlap or engage with one another, the other actuating element can only be actuated if a crescent-shaped recess, for example, of one actuating element is located in the overlapping area.

[0020] In a further development of this embodiment, the ball of the first ball valve is made of plastic and the ball of the second ball valve is made of metal, in particular steel, or vice versa. The plastic can be, for example, PTFE, i.e. polytetrafluoroethylene, which has a very low coefficient of friction, but other plastics are also possible, for example POM, i.e. polyoxymethylenes. A good sealing effect can be achieved if one of the two balls is made of plastic, i.e. a comparatively soft material, and the other ball is made of metal, i.e. a comparatively hard material. It is also possible for both balls to be made of a comparatively hard material, for example metal.

[0021] In the embodiment described here, the ball of the second ball valve engages the spherical cap-shaped recess of the first ball valve, so that the spherical cap-shaped recess of the first ball valve forms part of the lining of the second ball valve. Since the ball of the first ball valve has the spherical cap-shaped recess and plastic is easier to machine than metal, it is advantageous if the ball of the first ball valve is made of plastic and the ball of the second ball valve is made of metal. In principle, both coupling parts can be designed as fully lined ball valves.

[0022] In a further development, the first ball valve has a seal made of metal, in particular steel, and the second ball valve has a seal made of plastic, or vice versa. As described above, a good sealing effect is achieved between a soft and a hard material. Therefore, if the ball of the first ball valve is made of plastic, it is advantageous to seal it by means of a seal, e.g. in the form of a lining or a stuffing box made of metal, in particular steel. Accordingly, the ball of the second ball valve, which is made of metal, should be sealed by means of a seal in the form of a stuffing box or a lining, in particular a full lining, made of plastic. If the ball of the first ball valve is made of metal, it is sealed by a plastic seal.The ball of the second ball valve, which in this case is made of plastic, is sealed by a metal seal. The seal is formed on the inside of the housing of the respective ball valve, which in this case corresponds to the housing of the respective coupling part.

[0023] In an alternative embodiment, the two coupling parts each have a ball part, and the two ball parts form a ball of the shared ball valve. The two ball parts are typically substantially hemispherical and are occasionally referred to below as ball halves. If the two ball parts are adjacent to each other when the coupling is closed, their outer contour forms a sphere. In the embodiment described here, each ball part serves to shut off the respective power end to prevent fluid from escaping. In this embodiment, therefore, only a single - split - ball valve is required.

[0024] In a further development of this embodiment, the two ball parts are mounted for rotation about a common axis of rotation. The ball parts or the ball of a ball valve are usually provided with a shaft in order to rotate the ball between an open position allowing the passage of the liquid and a second position blocking the passage of the liquid. The angle of rotation between the two positions is usually 90°. The shaft is usually attached to the ball, but it is also possible for the ball to be formed integrally with the shaft, i.e. for the ball to have a protruding section that forms the shaft.

[0025] By rotating around the common axis of rotation, in the embodiment described here, the common ball valve, which has only one shaft, can be moved from an open position to a closed position and vice versa. To enable rotation, the shaft can have a polygonal pin or a polygonal recess, e.g., in the shape of a hexagon or the like. The pin or recess can be manually engaged by an operator or by an automated drive to rotate the ball of the ball valve between the two positions.

[0026] In a further development of this embodiment, a cylindrical passage opening for the passage of the liquid runs both in the first sphere part and in the second sphere part. In this case, the two sphere parts typically have a recess in the shape of part of the cross-section of a cylinder on their flat, mutually facing end faces, which, when the sphere parts are adjacent to one another, complement each other to form the cylindrical cross-section of the passage opening. The cross-section of the passage opening is thus divided between the two sphere parts. The recess in a respective sphere part or a respective sphere half can, for example, be designed in the manner of a cylinder halved along its longitudinal axis.

[0027] In the embodiment described here, the fluid within the passage typically escapes into the environment when the two coupling parts are separated. This embodiment is therefore particularly suitable for separating lines with a comparatively small diameter, since in this case, the amount of fluid escaping when the line sections are separated is comparatively small.

[0028] In an alternative embodiment, a cylindrical passage for the passage of the fluid runs through the first sphere part or the second sphere part. If the passage, which is typically designed as a through-bore, is completely relocated into one of the two sphere halves, the fluid is completely enclosed in the through-bore of the respective sphere half upon separation of the two coupling parts, i.e., leakage of the fluid is prevented.

[0029] In a further development of this embodiment, the common longitudinal axis of the line ends is offset with respect to a center of the sphere formed by the two spherical parts. In order to enable the passage opening to be formed in only one of the two spherical parts, as described in DE 100 19 526 A1, a spherical part or a spherical half can have a projection protruding from a flat end face, in which the cylindrical passage opening is formed. In the embodiment described here, however, the longitudinal axis of the two line ends is offset with respect to the center of the sphere formed by the two spherical parts. In this way, the passage bore can be formed in one of the two spherical parts without a projection having to be formed on one of the two spherical parts for this purpose, i.e. the two spherical halves do not have to engage with one another in this case.In this further development, the center of the ball is also offset laterally to the passage opening, ie the passage opening does not run centrally through the ball of the ball valve, as is otherwise usual.

[0030] In a further development of this embodiment, the ball parts—when the coupling parts are in contact with one another—have adjacent flat end faces. As described above, when an offset is provided between the center of the ball valve and the longitudinal direction of the line ends, it is possible for the two ball parts to have essentially the shape of hemispheres that do not engage with one another and are adjacent to one another at their flat end faces.

[0031] In a further embodiment, the coupling has a locking device to lock the two coupling parts at least in a position permitting the passage of fluid. Particularly in the position permitting the passage of fluid, it is necessary for the two coupling parts to be connected to one another in a fluid-tight manner. For this purpose, the coupling parts, or at least one of the coupling parts, generally have a seal. The locking device ensures that the two coupling parts of the coupling do not accidentally separate from one another and that fluid does not leak out. The locking device can be designed in different ways.For example, the locking device may comprise claws or the like on one coupling part, which engage with webs or the like on the other coupling part when the balls of the ball valves or the ball parts which complement the ball of the common ball valve are rotated into the position allowing the passage of the liquid.

[0032] In a further embodiment, an intermediate space, which is delimited from the environment by two seals, in particular an annular space delimited by two radial seals, is formed between the two detachably connected coupling parts of the coupling, which annular space can be subjected to a negative pressure in order to test the tightness of the coupling, wherein the coupling preferably has a further radial seal which is arranged radially inward of the two radial seals which delimit the annular space.

[0033] During a leak test, a test gas, such as helium, is typically passed through a line, and a check is made to see whether the test gas is detected in the area surrounding the line, which would indicate a leak in the line. This is not readily possible with the coupling described here, as the line would have to be emptied and possibly dried for this purpose. To still enable a leak test, a gap, usually an annular space, is formed between two seals, typically between two radial seals located between the end faces of the two coupling parts, in the coupling described here.

[0034] The two coupling parts are typically detachably connected to one another via a screw connection, for example using a flange. The radial seals, e.g. in the form of O-rings or the like, can be introduced into annular grooves provided on the end faces of the two coupling parts. The space between the seals can be subjected to negative pressure or evacuated via a suitable connection. In the event that the radially inner of the two seals is not sufficiently tight, the liquid is sucked into the space and can be detected by a suitable sensor. If the presence of liquid, e.g. water, is continuously detected in the space after a predetermined period of time, e.g. on the order of 10 minutes, the inner seal facing the line ends is not vacuum-tight.In case no liquid is detected, the seal or coupling is vacuum-tight.

[0035] It is possible to provide at least one additional radial seal between the two coupling parts, which is typically located radially inward of the two seals that define the annular space. The additional seal is redundant, i.e., it serves to increase the functional reliability of the coupling. If the inner of the two seals defining the gap and the additional seal are not vacuum-tight, the presence of fluid in the gap will also be detected, and the coupling will not be vacuum-tight.

[0036] A further aspect of the invention relates to a method for testing the tightness of the detachably connected coupling parts of the coupling of the lithography system according to the embodiment described above. The method comprises: releasing the respective line ends to allow the liquid to flow through the coupling parts, generating a negative pressure in the intermediate space, and checking whether the liquid gets into the intermediate space when the negative pressure is applied. To carry out the method, the coupling parts are typically moved into the open position to allow the liquid to flow through the line ends or to ensure that the liquid is present at the end faces of the two coupling parts and is in contact with the radially inner seal or the further seal. As described above, a negative pressure is generated in the intermediate space to check whether the liquid can pass through the seal or the further seal.through the two seals into the gap. If this is the case, the coupling is not vacuum-tight, and the seals should be replaced promptly. The presence of the radially outer seal, which defines the gap or annular space, ensures that no fluid initially escapes from the coupling into the vacuum environment in which the coupling is located during operation of the lithography system.

[0037] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details essential to the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0038] drawing

[0039] Examples of embodiments are shown in the schematic drawing and are explained in the following description.

[0040] Fig. 1 shows a meridional section of a projection exposure system for EUV projection lithography,

[0041] Fig. 2 is a schematic representation of a projection optics with a temperature control device, which has, for example, two lines, each with two line sections, which are connected to each other by means of a coupling,

[0042] Fig. 3a-d are schematic representations of an embodiment of the coupling of Fig. 2, in which two detachably connected coupling parts each have a ball valve, as well as actuating elements of the two ball valves, Fig. 3e is a schematic sectional view of the coupling with the actuating elements and with three radial seals between the end faces of the two coupling parts,

[0043] Fig. 4a, b schematic representations of a further embodiment of the coupling of Fig. 2, in which the two coupling parts together form a ball valve having a central passage opening, and

[0044] Fig. 5a-c schematic representations of an embodiment of the coupling analogous to Fig. 4a, b, in which the passage opening is formed in the second coupling part.

[0045] In the following description of the drawings, identical reference symbols are used for identical or functionally identical components.

[0046] The following describes, by way of example, the essential components of an optical arrangement for EUV lithography in the form of a projection exposure system 1 for microlithography with reference to Fig. 1. The description of the basic structure of the projection exposure system 1 and its components is not intended to be limiting.

[0047] An embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system. In this case, the illumination system does not include the light source 3. A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9.

[0048] For illustrative purposes, a Cartesian xyz coordinate system is shown in Fig. 1. The x-direction runs perpendicular to the drawing plane. The y-direction runs horizontally, and the z-direction runs vertically. The scanning direction in Fig. 1 runs along the y-direction. The z-direction runs perpendicular to the object plane 6.

[0049] The projection exposure system 1 comprises a projection system 10. The projection system 10 is used to image the object field 5 into an image field 11 in an image plane 12. A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0050] The radiation source 3 is an EUV radiation source. The radiation source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation has, in particular, a wavelength in the range between 5 nm and 30 nm. The radiation source 3 can be a plasma source, for example, an LPP source (laser produced plasma) or a DPP source (gas discharged produced plasma). It can also be a synchrotron-based radiation source. The radiation source 3 can be a free-electron laser (FEL).

[0051] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector mirror 17. The collector mirror 17 can be a collector mirror with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector mirror 17 can be exposed to the illumination radiation 16 at grazing incidence (Gl), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector mirror 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0052] After the collector mirror 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector mirror 17, and the illumination optics 4.

[0053] The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. The first facet mirror 20 comprises a plurality of individual first facets 21, which are also referred to below as field facets. Only a few of these facets 21 are shown in Fig. 1 as examples. A second facet mirror 22 is arranged downstream of the first facet mirror 20 in the beam path of the illumination optics 4. The second facet mirror 22 comprises a plurality of second facets 23.

[0054] The illumination optics 4 thus form a double-faceted system. This basic principle is also referred to as a fly's-eye integrator. With the help of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last beam-forming mirror, or actually the last mirror for the illumination radiation 16 in the beam path before the object field 5.

[0055] The projection system 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0056] In the example shown in Fig. 1, the projection system 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection system 10 is a double-obscured optical system. The projection optical system 10 has an image-side numerical aperture that is greater than 0.4 or 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0057] The mirrors Mi, just like the mirrors of the illumination optics 4, can have a highly reflective coating for the illumination radiation 16.

[0058] Fig. 2 shows a highly schematic view of a housing 25 of the projection optics 10 of Fig.

[0059] 1. In Fig. 2, a temperature control device 26 in the form of a cooling device for cooling the projection optics 10 is additionally shown. The temperature control device 26 has a pump 27 that supplies a liquid 28, indicated by an arrow in Fig. 2a, through a first pipe 29a to a first media connection 30a on the housing 25 of the projection optics 10. Starting from the first media connection 30a, the liquid 28, which in the example shown is cooling water, is divided into two lines 31, 32. Also within the housing 25 of the projection optics 10, the two lines 31, 32 are brought together again and open into a common second media connection 30b on the housing 25. At the second media connection 30b of the housing 25, the liquid 28 enters a second pipe 29b and is returned to the pump 27.

[0060] The temperature control device 26 of Fig. 2 is shown in a highly simplified manner, particularly within the projection optics 10: Typically, more than two lines 31, 32 extend from the first media connection 30a. A respective line 31, 32 can also branch into further lines within the housing 25 of the projection optics 10, which are then reconnected within the housing 25.

[0061] To simplify the illustration, only two line sections 31a, 31b; 32a, 32b of the two lines 31, 32 are shown in Fig. 2, which are adjacent to the media connections 30a, 30b. The line sections 31a, 32b; 32a, 32b of the respective line 31, 32 are detachably connected to one another by means of a coupling 33, 34. The respective coupling 33, 34 enables the separation of the two line sections 31a,b; 32a,b filled with the liquid 28 without the liquid 28 escaping or with the escaping of a small volume of liquid. The respective coupling 33, 34 has two detachably connected coupling parts or halves 33a, 33b; 34a, 34b and can be designed in different ways. Fig. 3a-d show an example of the coupling 33 of the two line sections 31a, 31b of the first line 31. In each of the two coupling parts 33a, 33b, a line end 35a, 35b of one of the two line sections 31a, 31b opens. As shown in Fig.As can be seen in Figure 3a, the two coupling parts 33a, 33b each have a channel for the passage of the fluid 28, which is adjacent to a respective line end 35a, 35b. The first coupling part 33a has a first ball valve 37a for blocking or releasing the first line end 35a of the first line section 31a. The second coupling part 33b has a second ball valve 37b for blocking or releasing the second line end 35b of the second line section 31b.

[0062] Each ball valve 37a, 37b has a ball 38a, 38b in which a central, circular-cylindrical through-opening or through-bore 39a, 39b is formed. In the position shown in Fig. 3a, the two ball valves 37a, 37b are open for the passage of the liquid 28, i.e., the longitudinal direction of the through-openings 39a, 39b is aligned parallel to the longitudinal axis of the line ends 35a, 35b, which corresponds to the X-direction of an XYZ coordinate system. The two balls 38a, 38b of the ball valves 37a, 37b are each rotatable about a rotational axis extending in the Z-direction in Fig. 3a-d. The rotation of the balls 38a, 38b of the two ball valves 37a, 37b is possible independently of one another. Both the first and second balls 38a, 38b can be rotated through an angle of 90° around the axis of rotation to block off the respective line end 35a, 35b or to open it for the passage of the liquid 28. Two elements shown in Fig. serve for the rotation through the angle of 90°.3a-c show a plan view of actuating elements 45a, 45b in the form of actuating pins that are attached to a respective ball 38a, 38b and that extend along the rotational axis of the respective ball 38a, 38b and can be rotated about it. As can be seen in Fig. 3a-c, the two actuating elements 45a, 45b, or more precisely, their circular outer contours, overlap in an overlapping area. The rotation or actuation of the two actuating elements 45a, 45b is only possible because the first actuating element 45a and the second actuating element 45b each have a crescent-shaped recess on the circular edge. The recesses of the two actuating elements 45a, 45b are aligned with each other in such a way that the first actuating element 45a can only be actuated in the open position of the second ball valve 37b, which is indicated by a horizontal double arrow.The second actuating element 45b, on the other hand, can only be actuated when the first ball valve 37a is in the closed position, which is indicated by a vertical double arrow. This ensures that the actuation sequence is maintained both when opening and closing the coupling 33.

[0063] As can also be seen in Fig. 3a-d, the ball 38a of the first ball valve 37a has a spherical cap-shaped recess 40 on its outer side. To release the coupling 33, the ball 38a of the first coupling part 33a is first rotated from the position shown in Fig. 3a for allowing the passage of the liquid 28 into the position shown in Fig. 3b, in which the first ball valve 37a blocks the first line end 35a. This takes advantage of the fact that the ball 38b of the second ball valve 37b is in the open position, so that the ball 38a of the first ball valve 37a can be guided past the ball 38b of the second ball valve 37b.

[0064] In a subsequent step, shown in Fig. 3c, the ball 38b of the second ball valve 37b is moved from the open position into the position blocking the second line end 35b, whereby the ball 38b of the second ball valve 37b engages the spherical cap-shaped recess 40 of the first ball valve 37a. In the position of the two ball valves 37a, b shown in Fig. 3c, both line ends 35a, b are blocked, and the two coupling parts 33a, 33b can be separated from one another without fluid 28 escaping, as shown in Fig. 3d.

[0065] In the example shown in Fig. 3a-d, the spherical cap-shaped recess 40 forms part of the lining of the ball 38b of the second ball valve 37b. The ball 38a of the first ball valve 37a is made of plastic, and the ball 38b of the second ball valve 37b is made of steel. The first ball valve 37a has a seal in the form of a steel lining 41a, which is formed on the inside of the housing of the first coupling part 33a in the region of the ball 38a. The second ball valve 37b has a seal in the form of a plastic lining 41b, which is formed on the inside of the housing of the second coupling part 33b in the region of the ball 38b. Instead of the linings 41a, 41b, stuffing boxes can also be used as seals.

[0066] Fig. 3e shows a detail of the coupling 33 of Fig. 3a-d in a longitudinal section, in which the two actuating pins 45a, 45b of Fig. 3a-c can be seen, which overlap along their outer contours. Also visible in Fig. 3e are the end faces 49a, 49b of the two coupling parts 33a, 33b, which adjoin one another when the two coupling parts 33a, 33b are detachably connected. The detachable connection can be realized in the form of a screw connection, for example, by screwing two flanges provided on the coupling parts 33a, 33b together so that the coupling parts 33a, 33b abut one another with their end faces 49a, 49b.To seal the coupling parts 33a, 33b from the environment, which is typically a vacuum environment, in the example shown, three annular seals 50a-c in the form of O-rings are attached to the coupling 33, which are inserted into a respective annular groove on the end faces 49a, 49b of the two coupling parts 33a, 33b. Between a first, radially inner seal 50a and a second, radially outer seal 50b, an annular space 51 is formed, which can be subjected to a negative pressure or vacuum via a suitable connection (not shown). A further, third seal 50c is arranged radially inward of the two seals 50a, 50b, which delimit the annular space 51. Typically, only two radial seals are used to seal the end face of the coupling 33 from the environment, with one of the two seals being redundant.

[0067] In the example shown, the annular space 51 between the two radial seals 50a, b is used to test the tightness of the detachably connected coupling parts 33a, 33b of the coupling 33. For this purpose, the line ends 35a, 35b are first released to allow the fluid 28 to flow through the coupling parts 33a, 33b by turning the two ball valves 37a, 37b to the open position in the manner described above. Subsequently, a negative pressure, typically a vacuum, is generated in the annular space 51 and it is checked whether the fluid 28 enters the annular space 51 when the negative pressure is applied. If this is the case, both the first seal 50a and the third, radially inner seal 50c are not vacuum-tight, i.e. the coupling 33 as a whole is not vacuum-tight. If no liquid 28 is detected during the test, the coupling 33 has passed the leak test and can be used or continued to be used.

[0068] Fig. 4a, b show a coupling 33 which differs from the coupling 33 shown in Fig. 3a-d in that the two coupling parts 33a, 33b together form a ball valve 37. For this purpose, the coupling parts 33a, 33b each have a ball part 42a, 42b. The two ball parts 42a, 42b rest against one another and form a ball 48 of the common ball valve 37. As can be seen in Fig. 4b, which is a sectional view along the line AA of Fig. 4a, the two ball parts 42a, 42b are rotatably mounted about a common axis of rotation 43. The two ball parts 42a, 42b each have a shaft section 44a, 44b protruding from the outer contour of the ball 42 and extending within the respective coupling part 33a, 33b. The two shaft sections 44a, 44b can be rotated together about the rotation axis 43.For this purpose, an operator or an automated drive can engage a polygonal recess 46, which in the example shown has the geometry of a hexagon, on the end face of the first shaft section 44a. The line sections 31a, 31b and the line ends 35a, 35b are not shown in Fig. 4a, b.

[0069] As can be seen in Fig. 4b, which shows the coupling 33 in a closed position, the passage opening 39 of the ball 42 of the ball valve 37 extends within both the first and second ball parts 42a, 42b. More precisely, one half of the cross-section of the cylindrical passage opening 39 extends within the first ball part 42a and the other half within the second ball part 42b. The two ball parts 42a, 42b each have a correspondingly designed recess for this purpose. The fluid 28 located in the passage opening 39 escapes into the environment when the two coupling parts 33a, 33b are separated.

[0070] As also indicated in Fig. 4b, the coupling 33 has a locking device 47 for locking the two coupling parts 33a, 33b at least in a position allowing the passage of the liquid 28. The locking device 47 has a claw (not shown) that is attached to the shaft portion 42b of the second ball part 42b and that is rotated about the rotation axis 43 for locking and is thereby engaged with a pin to lock the two coupling parts 33a, 33b. The locking device 47 can correspondingly also have a claw on the other shaft portion 42a, which is engaged with a corresponding pin for locking. It is understood that the locking device 47 can also be designed in a different way.

[0071] Fig. 5a-c show a coupling 33 which, like the coupling 33 shown in Fig. 4a, b, has two spherical parts 42a, 42b which complement each other to form a sphere 42. Unlike in Fig. 4a, b, in Fig. 5a-c the passage opening 39 does not run centrally through the ball 42 of the ball valve 37, but is laterally offset from it and is formed only in the second spherical part 42b. The longitudinal axis L of the line ends 35a, 35b of the two line sections 31a, 31b, shown in dashed lines in Fig. 5a, is laterally offset from the center Z of the ball 42 of the ball valve 37. The two spherical parts 42a, 42b are designed in the shape of hemispheres, each having a flat end face 48a, 48b. The end faces 48a, 48b are adjacent to each other when the two ball parts 42a, 42b form the ball 42 of the ball valve 37.

[0072] The ball 42 of the ball valve 37 is moved from the position shown in Fig. 5a, which allows the passage of the liquid 28, to a position shown in Fig. 5b, which blocks the passage of the liquid 28, by rotating the ball 42 of the ball valve 37 by 90°. The liquid 28 located within the passage opening 39 is enclosed in the second coupling part 33b and does not escape into the environment when the two coupling parts 33a, 33b are separated from each other, as shown in Fig. 5c.

[0073] The coupling 33 described above can almost completely prevent the escape of fluid 28 from the line sections 31a, 31b when the two coupling parts 33a, 33b are separated. Due to the cylindrical shape of the passage opening 39, the flow of fluid 28 is not impeded as it passes through the coupling 33, meaning that no vortex formation occurs and flow-induced vibrations can be avoided.

[0074] The coupling 33 described above can also be used elsewhere in the EUV lithography system 1 or in other lithography systems or semiconductor technology systems to detachably connect line sections 31a, 31b; 32a, 32b, ... to one another, for example in the illumination optics 4. The respective line 31, 32 does not necessarily have to be part of a temperature control device; rather, it can also be part of another type of device that uses lines through which a liquid can flow. It is understood that the leakage test described above in connection with Fig. 3e can also be performed analogously in the examples described in Figs. 4a, b and 5a-c.

Claims

Patent claims 1. Lithography system, in particular an EUV lithography system (1), comprising: a device, preferably a temperature control device (26), which has at least one line (31, 32) for the flow of a liquid (28), characterized in that the line (31) comprises two line sections (31a, 31b) which are connected to one another by means of a coupling (33), wherein the coupling (33) has two detachably connected coupling parts (33a, 33b), into which a line end (35a, 35b) of one of the two line sections (34a, 34b) opens, and wherein the coupling parts (33a, 33b) each have a ball valve (37a, 37b) for blocking or releasing the respective line end (35a, 35b) or wherein the coupling parts (33a, 33b) together have a ball valve (37) form.

2. Lithography system according to claim 1, in which a ball (38a) of the first ball valve (37a) of the first coupling part (33a) has a spherical cap-shaped recess (40) into which a ball (38b) of the second ball valve (37b) of the second coupling part (33b) engages in a position of the two ball valves (37a, 37b) blocking the line ends (35a, 35b).

3. Lithography system according to claim 2, wherein the first ball valve (37a) has a first actuating element (45a) for rotating the ball (38a) of the first ball valve (37a) and the second ball valve (37b) has a second actuating element (45b) for rotating the ball (38b) of the second ball valve (37b), wherein the first actuating element (45a) is only operable in an open position of the second ball valve (37b) and the second actuating element (45b) is only operable in a closed position of the first ball valve (37a), or vice versa.

4. Lithography system according to claim 2 or 3, wherein the ball (38a) of the first ball valve (37a) is formed from plastic and the ball (38b) of the second ball valve (37b) is formed from metal, in particular from steel, or vice versa.

5. Lithography system according to claim 4, wherein the first ball valve (37a) has a seal (41a) made of metal, in particular steel, and wherein the second ball valve (37b) has a seal (41b) made of plastic, or vice versa.

6. Lithography system according to claim 1, wherein the two coupling parts (33a, 33b) each have a ball part (42a, 42b) and the two ball parts (42a, 42b) form a ball (42) of the common ball valve (37).

7. Lithography system according to claim 6, wherein the two ball parts (42a, 42b) are mounted rotatably about a common axis of rotation (43).

8. Lithography system according to claim 6 or 7, wherein a cylindrical passage opening (39) for the passage of the liquid (28) extends both in the first spherical part (42a) and in the second spherical part (42b).

9. Lithography system according to claim 6 or 7, wherein a cylindrical passage opening (39) for the passage of the liquid (28) extends only in the first spherical part (42a) or only in the second spherical part (42b).

10. Lithography system according to claim 9, wherein the longitudinal axis (L) of the line ends (35a, 35b) is arranged offset with respect to a center (Z) of the sphere (42) formed by the two sphere parts (42a, 42b). H . Lithography system according to claim 9 or 10, wherein the spherical parts (42a, 42b) have adjacent planar end faces (48a, 48b).

12. Lithography system according to one of the preceding claims, wherein the coupling (33) has a locking device (47) for locking the two coupling parts (33a, 33b) at least in a position allowing the passage of the liquid (28).

13. Lithography system according to one of the preceding claims, in which an intermediate space is formed between the two detachably connected coupling parts (33a, 33b) of the coupling (33), which intermediate space is delimited from the environment by two seals, in particular an annular space (51) delimited by two radial seals (50a, 50b), which can be subjected to a negative pressure in order to test the tightness of the coupling (33), wherein the coupling (33) preferably has a further radial seal (50c) which is arranged radially inwardly of the two radial seals (50a, 50b) which delimit the annular space (51).

14. A method for testing the tightness of the detachably connected coupling parts (33a, 33b) of the coupling (33) of the lithography system according to claim 13, comprising: Releasing the line ends (35a, 35b) to allow the fluid (28) to flow through the coupling parts (33a, 33b), generating a negative pressure in the intermediate space (51), and checking whether the fluid (28) enters the intermediate space (51) when the negative pressure is applied.

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